I877.] MR. E. A. SMITH ON SHELLS FROM LAKE NYASSA. 717 



tire surl'ace is covered with faint spiral striae, which are distinctly 

 visible to the naked eye. The very shallow depression around the 

 middle of the body-whorl in the type specimen I am inclined to re- 

 gard as an individual pecularity, and not a specific character ; for 

 there is no trace of such a furrow in any of the shells just received. 

 These, for the most part, have the spire rather more elongated than 

 the type, and the umbilicus a trifle narrower. 



13. Paludina capillata, Frauenfeld. (Plate LXXIV. figs. 

 3, 4.) 



Vivipara capillata, Frfld. P. Z. S. 1865, p. 659. 

 Hab. Lake Nyassa (Dr. Kirh). 



14. Paludina robertsoni, Frauenfeld. (Plate LXXIV. figs. 

 5,6.) 



Vivipara capillata, Frfld. I. c. 

 Hab. Same as preceding species. 



15. Paludina polita, Frauenfeld. 



Paludina polita, Frfld. ; Reeve, Conch. Icon. xiv. sp. 73, fig. 73 ; 

 Dohrn, P. Z. S. 1865, p. 233. 



Hab. South Africa (?). Lake Nyassa {Dr. Kirk). 



16. Bythinia stanleyi, sp. nov. (Plate LXXV. figs. 21, 22.) 

 Shell small, ovate, rather solid, subrimate, dirty white or yellow- 

 ish, obliquely striated by the lines of growth ; whorls four, slowly 

 increasing, very convex ; suture simple, rather deep ; mouth sub- 

 circular, occupying about half the whole length of the shell ; peri- 

 stome stout, thickened. 



Length 5 millims., diam. 3^. 



Hab. Lake Nyassa. 



The sohdity, very convex whorls, and subcircular aperture, are 

 the chief distinguishing characteristics of this little shell. The 

 operculum, of course, takes the form of the mouth, and has the 

 lines of increment rather coarse near the margins. 



I dedicate this little shell to Mr. Henry M. Stanley, as a mark of 

 admiration of his undaunted perseverance and achievements in 

 African exploration. 



17. Physa nyassana, sp. nov. (Plate LXXV. figs. 16, 17.) 

 Shell solid, pale olive-brown, narrowly perforate, somewhat trian- 

 gular, roundly angulated above, and with a very short depressed 

 spire ; whorls five, convex, separated by a deep channelled suture, 

 and sculptured by fine lines of growth ; last whorl very large, occu- 

 pying almost the entire length of the shell, since the spire is very 

 shortly conical and only slightly elevated ; aperture large, only a 

 trifle shorter than the whorl, subauriform ; columella thickened and 

 a little reflexed, subtortuous, and connected with the upper ex- 

 tremity of the outer lip by a thin callous deposit upon the whorl. 



Proc. Zool. Soc— 1877, No. XLVII. 47 



